Data transmission method and communications apparatus

ABSTRACT

This application relates to the field of communications technologies, and provides a data transmission method and a communications apparatus, to reduce complexity and overheads of data reception performed by a base station. The method includes: receiving information about a repetition quantity R1 corresponding to Tmax, where Tmax is a maximum transport block size allowed to be used to transmit data; determining a cyclic parameter L based on R1, where the cyclic parameter L indicates that content carried in each of a plurality of time units to which a transport block used to transmit the data is mapped is repeated in L consecutive time units, and wherein a size of the transport block used to transmit the data is Ts, and Ts&lt;Tmax; and transmitting the data based on the cyclic parameter L.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/095,491, filed on Nov. 11, 2020, which is a continuation ofInternational Application No. PCT/CN2019/086614, filed on May 13, 2019,which claims priority to Chinese Patent Application No. 201810451021.3,filed on May 11, 2018. All of the afore-mentioned patent applicationsare hereby incorporated by reference in their entireties.

TECHNICAL FIELD

This application relates to the field of communications technologies,and in particular, to a data transmission method and a communicationsapparatus.

BACKGROUND

In a data transmission process, because a network side usually cannotlearn of a transport block size required by a terminal to transmit data,the network side usually notifies the terminal of a maximum TBS (denotedas Tmax) that the terminal is allowed to use to transmit the data. A TBS(denoted as Ts) actually used by the terminal to transmit the data maybe less than Tmax. To avoid a waste of resources and reduce powerconsumption of the terminal, the network side usually supports theterminal in selecting Ts less than Tmax to transmit the data. Due todiversity of data transmission on an existing network, in the foregoingscenario, how to minimize processing complexity of a network device is aproblem to be resolved.

SUMMARY

This application provides a data transmission method and an apparatus,to reduce complexity and overheads of data reception performed by anetwork device.

According to a first aspect, this application provides a datatransmission method. The method includes: receiving information about arepetition quantity R1 corresponding to Tmax, where Tmax is a maximumtransport block size allowed to be used to transmit data; determining acyclic parameter L based on R1, where the cyclic parameter L indicatesthat content carried in each of a plurality of time units to which atransport block used to transmit the data is mapped is repeated in Lconsecutive time units, and wherein a size of the transport block usedto transmit the data is Ts, and Ts<Tmax; and transmitting the data basedon the cyclic parameter L.

According to the data transmission method provided in this application,the cyclic parameter L may be determined based on R1 indicated by anetwork device, so that values of L are the same regardless of a valueof Ts used by a terminal device to transmit the data, and the networkdevice does not need to assume different cyclic parameters L to processreceived data. This reduces processing complexity and receivingoverheads of the network device in a process of receiving the data.

Optionally, before the transmitting the data based on the cyclicparameter L, the method further includes: determining R2 based on Ts,R1, and L, where R2 is an integer multiple of L, and R2 is a totalquantity of repeated transmissions of the content carried in each timeunit when the data is sent. The transmitting the data based on thecyclic parameter L includes: transmitting the data based on the cyclicparameter L and R2.

In this optional manner, a calculated actual repetition quantity R2 ofthe transport block whose size is Ts is an integer multiple of L. Thiscan ensure that the terminal device sends the data for a plurality of(R2/L) complete sending cycles, and improve data transmissionefficiency.

Optionally, the receiving information about a repetition quantity R1corresponding to Tmax includes: receiving a random access response RARmessage, where the information about R1 is carried in the RAR message.The transmitting the data based on the cyclic parameter L includes:transmitting the data through a third message, namely, an MSG 3, duringa random access procedure based on the cyclic parameter L.

According to a second aspect, this application provides a datatransmission method. The method includes: sending, to a terminal device,information about a repetition quantity R1 corresponding to Tmax, whereTmax is a maximum transport block size allowed to be used; determining acyclic parameter L based on R1, where the cyclic parameter L indicatesthat content carried in each of a plurality of time units to which atransport block used to transmit data is mapped is repeated in Lconsecutive time units, and wherein a size of the transport block usedto transmit the data is Ts, and Ts<Tmax; and receiving the data based onthe cyclic parameter L.

According to the data transmission method provided in this application,the cyclic parameter L used by the terminal device may be determinedbased on R1 indicated by a network device, so that values of L are thesame regardless of a value of Ts used by the terminal device to transmitthe data, and the network device does not need to assume differentcyclic parameters L to process received data. This reduces processingcomplexity and receiving overheads of the network device in a process ofreceiving the data.

Optionally, before the receiving the data based on the cyclic parameterL, the method further includes: determining R2 based on Ts, R1, and L,where R2 is an integer multiple of L, and R2 is a total quantity ofrepeated transmissions of the content carried in each time unit when theterminal device sends the data. The receiving the data based on thecyclic parameter L includes: receiving the data based on the cyclicparameter L and R2.

In this optional manner, a calculated actual repetition quantity R2 ofthe transport block whose size is Ts is an integer multiple of L. Thiscan ensure that the terminal device sends the data for a plurality of(R2/L) complete sending cycles, and improve data transmissionefficiency.

Optionally, the sending, to a terminal device, information about arepetition quantity R1 corresponding to Tmax includes: sending a randomaccess response RAR message to the terminal device, where theinformation about R1 is carried in the RAR message. The receiving thedata based on the cyclic parameter L includes: receiving the datathrough a third message, namely, an MSG 3, during a random accessprocedure based on the cyclic parameter L.

With reference to the first aspect or the second aspect, optionally, thedetermining a cyclic parameter L based on R1 satisfies L=min(K,┌R1/2┐),where min represents taking a minimum value, K is a preset constant, and┌ ┐ represents rounding up.

Optionally, the determining R2 based on Ts, R1, and L satisfiesR2=(L*┌f(Ts,R1)/L┐), where ┌ ┐ represents rounding up.

Optionally, f(Ts,R1) satisfies f(Ts,R1)=(Ts/Tmax)*R1.

According to a third aspect, a data transmission method is provided. Themethod includes: receiving information about a repetition quantity R1corresponding to Tmax, where Tmax is a maximum transport block sizeallowed to be used to transmit data; determining R2 based on Ts, R1, anda cyclic parameter L, where R2 is an integer multiple of L, the cyclicparameter L indicates that content carried in each of a plurality oftime units to which a transport block used to transmit the data ismapped is repeated in L consecutive time units, R2 is a total quantityof repeated transmissions of the content carried in each time unit whenthe data is sent, a size of the transport block used to transmit thedata is Ts, Ts<Tmax, and R2<R1; and sending the data based on R2.

According to the data transmission method provided in this application,a method for reducing the repetition quantity R1 is provided, so thatwhen Ts is less than Tmax, a terminal device can reduce R1 to obtain R2(where R2<R1), to reduce sending power consumption of the terminal.

According to a fourth aspect, this application provides a datatransmission method. The method includes: sending, to a terminal device,information about a repetition quantity R1 corresponding to Tmax, whereTmax is a maximum transport block size allowed to be used to transmitdata; calculating R2 based on Ts, R1, and a cyclic parameter L, where R2is an integer multiple of L, the cyclic parameter L indicates thatcontent carried in each of a plurality of time units to which atransport block used to transmit the data is mapped is repeated in Lconsecutive time units, R2 is a total quantity of repeated transmissionsof the content carried in each time unit when the data is sent, a sizeof the transport block used to transmit the data is Ts, Ts<Tmax, andR2<R1; and receiving the data based on R2.

According to the data transmission method provided in this application,a method for reducing the repetition quantity R1 is provided, so thatwhen Ts is less than Tmax, the terminal device can reduce R1 to obtainR2 (where R2<R1), to reduce sending power consumption of the terminal.

With reference to the third aspect and the fourth aspect, optionally,the determining R2 based on Ts, R1, and L satisfies R2=(L*┌f(Ts,R1)/L┐),where ┌ ┐ represents rounding up.

Optionally, f(Ts,R1) satisfies f(Ts,R1)=(Ts/Tmax)*R1.

Optionally, a value of the cyclic parameter L is fixed, or is determinedbased on R1.

Optionally, determining the cyclic parameter L based on R1 satisfiesL=min (K,┌R1/2┐), where min represents taking a minimum value, K is apreset constant, and ┌ ┐ represents rounding up.

In this optional manner, an actual repetition quantity, calculatedaccording to a preset scaling rule, of the transport block whose size isTs is an integer multiple of L. This can ensure that the terminal devicesends the data for a plurality of (R2/L) complete sending cycles, andimprove data transmission efficiency.

According to a fifth aspect, a communications apparatus is provided. Thecommunications apparatus has functions of implementing the terminaldevice in the method designs of the first aspect or the third aspect.The functions may be implemented by hardware, or may be implemented byhardware executing corresponding software. The hardware or the softwareincludes one or more units corresponding to the foregoing functions.

According to a sixth aspect, a communications apparatus is provided. Thecommunications apparatus has functions of implementing the networkdevice in the method designs of the second aspect or the fourth aspect.The functions may be implemented by hardware, or may be implemented byhardware executing corresponding software. The hardware or the softwareincludes one or more units corresponding to the foregoing functions.

According to a seventh aspect, a communications apparatus is provided,including a processor and a memory. The memory is configured to store aprogram or instructions. The processor is configured to invoke theprogram or the instruction from the memory and run the program or theinstruction, so that the communications apparatus performs the methodaccording to the first aspect or the third aspect.

Optionally, the communications apparatus may further include atransceiver, configured to support the communications apparatus insending and receiving data, signaling, or information in the methodaccording to the first aspect, for example, receiving the informationabout R1 or sending the data.

Optionally, the communications apparatus may be a terminal device, ormay be a part of an apparatus in a terminal device, for example, a chipsystem in the terminal device. Optionally, the chip system is configuredto support the terminal device in implementing functions in theforegoing aspects, for example, generating, receiving, sending, orprocessing data and/or information in the foregoing methods. In apossible design, the chip system further includes a memory, and thememory is configured to store a program instruction and data that arenecessary for the terminal device. The chip system includes a chip, andmay further include another discrete device or circuit structure.

According to an eighth aspect, a communications apparatus is provided,including a processor and a memory. The memory is configured to store aprogram or instructions. The processor is configured to invoke theprogram or the instructions from the memory and run the program or theinstructions, so that the communications apparatus performs the methodaccording to the second aspect or the fourth aspect.

Optionally, the communications apparatus may further include atransceiver, configured to support the communications apparatus insending and receiving data, signaling, or information in the methodaccording to the second aspect, for example, sending the informationabout R1 or receiving the data.

Optionally, the communications apparatus may be a network device, or maybe a part of an apparatus in a network device, for example, a chipsystem in the network device. Optionally, the chip system is configuredto support the network device in implementing functions in the foregoingaspects, for example, generating, receiving, sending, or processing dataand/or information in the foregoing methods. In a possible design, thechip system further includes a memory, and the memory is configured tostore a program instruction and data that are necessary for the networkdevice. The chip system includes a chip, and may further include anotherdiscrete device or circuit structure.

According to a ninth aspect, this application provides a computerstorage medium. The computer storage medium stores instructions. Whenthe instructions are run on a computer, the computer is enabled toimplement the data transmission method according to the first aspect,the optional manners of the first aspect, the second aspect, theoptional manners of the second aspect, the third aspect, the optionalmanners of the third aspect, the fourth aspect, or the optional mannersof the fourth aspect.

According to a tenth aspect, this application provides a computerprogram product including instructions. When the computer programproduct runs on a computer, the computer is enabled to implement thedata transmission method according to the first aspect, the optionalmanners of the first aspect, the second aspect, the optional manners ofthe second aspect, the third aspect, the optional manners of the thirdaspect, the fourth aspect, or the optional manners of the fourth aspect.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of a communications system according tothis application;

FIG. 2 is a schematic diagram of values of a cyclic parameter L in theprior art;

FIG. 3 is a flowchart 1 of an embodiment of a data transmission methodaccording to this application;

FIG. 4 is a flowchart 2 of an embodiment of a data transmission methodaccording to this application;

FIG. 5 is a flowchart 3 of an embodiment of a data transmission methodaccording to this application;

FIG. 6A is a flowchart 4 of an embodiment of a data transmission methodaccording to this application;

FIG. 6B is a flowchart 5 of an embodiment of a data transmission methodaccording to this application;

FIG. 7 is a schematic structural diagram of a communications apparatusaccording to this application; and

FIG. 8 is a schematic structural diagram of another communicationsapparatus according to this application.

DESCRIPTION OF EMBODIMENTS

The term “and/or” in this specification indicates that threerelationships may exist. For example, A and/or B may indicate thefollowing three cases: Only A exists, both A and B exist, and only Bexists.

A data transmission method provided in this application may be appliedto an LTE system, a long term evolution-advanced (LTE advanced, LTE-A)system, and a subsequent evolved system of the LTE system, for example,a fifth generation (5G) communications system, a new radio (new radio,NR) system, and a next-generation wireless local area network system.

For example, FIG. 1 is a schematic diagram of a communications systemaccording to this application. The data transmission method provided inthis application may be applied to any communications system includingat least one network device and at least one terminal device. Thenetwork device may be a base station (base station, BS) or a basetransceiver station device (base transceiver station, BTS), and is anapparatus deployed on a radio access network and configured to provide awireless communication function for the terminal device. In systemsusing different wireless access technologies, a device having a basestation function may have different names. For example, the device isreferred to as an evolved NodeB (evolved NodeB, eNB or eNodeB) on an LTEnetwork, a NodeB (Node B) on a third generation (3G) communicationsnetwork, a gNB applied to a fifth generation communications system, orthe like. For ease of description, the foregoing devices having the basestation function are collectively referred to as the network device inthis application.

The terminal device in this application may include various handhelddevices, vehicle-mounted devices, wearable devices, computing devices,smartphones, smartwatches, tablet computers, and the like that have awireless communication function. For ease of description, the foregoingdevices are collectively referred to as the terminal device in thisapplication.

The data transmission method provided in this application is applicableto a data transmission scenario: The network device cannot learn of atransport block size required by the terminal device to transmit data,and therefore, broadcasts a fixed maximum transport block size(transport block size, TBS) through a system message to indicate amaximum transport block size (denoted as Tmax) that the terminal deviceis allowed to use to transmit the data.

In this scenario, the terminal device usually sends the data in a cyclicrepetition (cyclic repetition) transmission mode. This transmission modeis related to two parameters: a repetition quantity R and a cyclicparameter L. R is a total quantity of repeated transmissions of contentcarried in each of a plurality of (assumed to be X) time units to whicha transport block (transport block, TB) used by the terminal device totransmit the data is mapped. R may be understood as a total quantity ofrepeated transmissions of the transport block used to transmit the data.

L indicates that the content carried in each time unit is repeated in Lconsecutive time units. Specifically, when sending the data based on R,after mapping the transport block to the X time units, the terminaldevice does not repeat, for R times, one sending cycle of the X timeunits carrying different content. Instead, the content carried in eachof the X time units is first repeated in the L consecutive time units,information in the X time units is sent in one sending cycle of X*L timeunits, and then the sending cycle is repeated for └R/L┘ times, where └ ┘represents rounding down. It should be noted herein that redundancyversions (redundancy version, RV) of different sending cycles may bedifferent. For example, an RV of a j^(th) sending cycle isrv_(idx)(j)=2□ mod(rv_(DCI)+j, 2), where rv_(DCI) is an initial RV, andmay be indicated in a random access response (random access response,RAR) or downlink control information (downlink control information,DCI).

In the prior art, a value of L is determined based on the repetitionquantity R actually used by the terminal device, and a relationshipbetween R and L satisfies L=min (4,┌R/2┐), where ┌ ┐ represents roundingup.

A cyclic repetition sending mode on a narrowband physical uplink sharedchannel (narrowband physical uplink shared channel, NPUSCH) in anarrowband internet of things (narrow band internet of things, NB-IoT)is used as an example. A transport block (or a codeword (codeword))corresponding to the NPUSCH is mapped to N_(RU) resource units (resourceunit, RU), and one of the N_(RU) RUs corresponds to N_(slots) ^(UL)slots (slot) in terms of time. Therefore, content of one NPUSCHtransport block is mapped to N_(RU)*N_(slots) ^(UL) slots.

It is assumed that R1 is a repetition quantity R indicated by a networkdevice, and R2 is an actual total repetition quantity corresponding toselected Ts. A cyclic parameter L is calculated based on R2: L=min(4,┌R2/2┐). When a terminal device sends data based on the cyclicparameter L and R2, the NPUSCH transport block is finally sent in Nconsecutive NB-IoT uplink slots, where N=R2*N_(RU)*N_(slots) ^(UL). Forease of description, the N consecutive uplink slots are numbered anddenoted as Ni, where i=0, 1, 2, 3, . . . , or N. During sending, the Nslots are divided into R2/L groups, and each group includes Bconsecutive uplink slots, where B=L*N_(RU)*N_(slots) ^(UL). Content thatis of the NPUSCH transport block and that is mapped to a

$\left\lfloor \frac{b}{L} \right\rfloor^{th}$slot (where b=0, 1, 2, . . . , or B−1) is sent in L uplink slots, andnumbers corresponding to the L uplink slots Ni are

${i = {{jB} + {2L\left\lfloor \frac{b}{2L} \right\rfloor} + {2l} + {{mod}\ \left( {\left\lfloor \frac{b}{L} \right\rfloor,2} \right)}}},$l=0, 1, . . . , L−1.

Corresponding to this application, in the foregoing example, the NPUSCHtransport block is mapped to X time units, where the time unit is twoslots (that is, one subframe), and X is

$\left\lfloor \frac{B}{2L} \right\rfloor.$One sending cycle corresponds to one group in this example. Contentcarried in each time unit (subframe) is repeated in L consecutivesubframes in one sending cycle. After content in

$\left\lfloor \frac{B}{2L} \right\rfloor*L$subframes is sent in one sending cycle of the

$\left\lfloor \frac{B}{2L} \right\rfloor*L$subframes (that is,

$\left\lfloor \frac{B}{2L} \right\rfloor*L*2$slots), the sending cycle is repeated for R2/L times. It should be notedherein that RVs of different sending cycles may be different. Forexample, an RV of a j^(th) sending cycle is rv_(idx)(j)=2□ mod(rv_(DCI)+j,2), where rv_(DCI) is an initial RV, and may be indicated ina RAR or DCI.

However, in some cases, Tmax indicated by the network device may begreater than a transport block size required by the terminal device totransmit the data. To avoid a waste of resources and reduce powerconsumption of the terminal, the network device usually supports theterminal device in selecting Ts (indicating a transport block sizeactually used by the terminal device to send the data) less than Tmax totransmit the data. When the network device schedules an uplink resourcefor the terminal device, the indicated repetition quantity R1corresponds to Tmax indicated by the network device. In other words,when a transport block size used by the terminal device to transmit thedata is Tmax (Ts=Tmax), the terminal device may send the data based onR1 (using R1 as a repetition quantity for sending). If Ts actually usedby the terminal device to transmit the data is less than Tmax, theterminal device reduces R1 to reduce sending power consumption of theterminal device. In other words, a repetition quantity R (assumed to beR2) actually used by the terminal device may be less than R1, and may becalculated according to a preset rule.

When selected Ts is less than Tmax, according to an existing mechanism,a value of L is determined based on the repetition quantity R2 actuallyused by the terminal device, and a relationship between R2 and Lsatisfies L=min (4,┌R2/2┐), where ┌ ┐ represents rounding up. When Tsselected by the terminal is different, R2 changes accordingly, and thevalue of L may also change. When L changes, a length of the sendingcycle also changes.

For example, as shown in FIG. 2 , it is assumed that a transport blockused by the terminal device to transmit the data is mapped to four timeunits, and content carried in the four time units is represented by 0,1, 2, and 3. When Ts=Tmax=1000 bits (bits), and R2=R1=16, L=4, onesending cycle includes 4*4=16 time units, and there are four sendingcycles in total. In one sending cycle, the content 0, 1, 2, and 3 eachare repeated in four consecutive time units.

When Ts=776 bits, and R2 corresponding to Ts is 12, L=4, one sendingcycle includes 4*4=16 time units, and there are three sending cycles intotal. In one sending cycle, the content 0, 1, 2, and 3 each arerepeated in four consecutive time units.

When Ts=536 bits, and R2=8, L=4, one sending cycle includes 4*4=16 timeunits, and there are two sending cycles in total. In one sending cycle,the content 0, 1, 2, and 3 each are repeated in four consecutive timeunits.

When Ts=328 bits, and R2=4, L=2, one sending cycle includes 4*2=8 timeunits, and there are two sending cycles in total. In one sending cycle,the content 0, 1, 2, and 3 each are repeated in two consecutive timeunits.

It can be learned that when Ts=328 bits, a value of L and a length ofthe sending cycle are different from those when Ts=1000 bits, Ts=776bits, and Ts=328 bits. Because the network device does not know aspecific value of Ts, when receiving the data sent by the terminaldevice, the network device needs to assume, based on different values ofTs, values of L and lengths of the sending cycle that correspond todifferent values of Ts, and attempt to perform signal combination anddemodulation on the data sent by the terminal. This causes relativelyhigh processing complexity and receiving overheads of the network devicein a process of receiving the data.

In view of this, this application provides a data transmission method.Values of L are the same regardless of a value of Ts used by theterminal device to transmit the data, and the network device does notneed to assume different cyclic parameters L to process received data.This reduces processing complexity and receiving overheads of thenetwork device in a process of receiving the data.

FIG. 3 is a flowchart of an embodiment of a data transmission methodaccording to this application. The method includes the following steps.

Step 301: A network device sends, to a terminal device, informationabout a repetition quantity R1 corresponding to Tmax.

The information about R1 may directly indicate a value of R1, or may bean index (index), and the terminal device may determine, based on apreset correspondence, a value of R1 corresponding to the index.

Step 302: The terminal device determines a cyclic parameter L based onR1.

In this application, after obtaining R1 indicated by the network device,the terminal device may determine L based on R1. For example, R1 and Lmay satisfy L=min (K,┌R1/2┐), where K is a preset constant, andindicates an allowed maximum value.

Optionally, R1 and L may alternatively satisfy the followingrelationship:

when R1≥M, L=min (K,┌R1/2┐); or

when R1<M, L=1; where M is a preset threshold, for example, M=8.

In another embodiment of this application, the terminal devicedetermines the cyclic parameter L based on a configuration or anindication of the network device. For example, the repetition quantityR1 corresponding to Tmax and the cyclic parameter L are both configuredor indicated by the network device.

Step 303: The terminal device sends data based on L.

In this application, because R1 is a repetition quantity specified bythe network device, L determined by the terminal device based on R1 isthe same regardless of whether Ts used by the terminal is less thanTmax.

In other words, when Ts<Tmax, the cyclic parameter L used by theterminal device is determined based on the repetition quantity R1, anddoes not vary with Ts.

Step 304: The network device determines L based on R1.

Step 305: The network device receives the data based on the cyclicparameter L.

A specific manner of determining L by the network device based on R1 isthe same as a manner of determining L by the terminal device based onR1. Therefore, the network device may clearly learn of a value of L usedby the terminal device, and accurately receive, based on the determinedL, the data sent by the terminal device. The network device does notneed to assume different values of Ts to calculate values of L that maybe used by the terminal device, and attempt to receive the data based onthe calculated different values of L. This reduces processing complexityand receiving overheads of the network device in a process of receivingthe data.

Optionally, with reference to FIG. 3 , as shown in FIG. 4 , before step303 is performed, the method further includes:

Step 306: The terminal device determines R2 based on Ts, R1, and L,where R2 is an integer multiple of L.

The terminal device may determine Ts based on Tmax and a data volume ofto-be-transmitted data.

For example, the terminal may first determine a corresponding TBS set{T1, T2, T3, T4} based on Tmax, and then select, from the set as Ts, asmallest TBS that can carry the data volume of the data. For example,the TBS set corresponding to Tmax may be shown in Table 1.

TABLE 1 Tmax 328 408 504 584 680 808 936 1000 T1 328 328 328 328 328 328328  328 T2 408 408 408 456 504 504  536 T3 504 504 584 680 712  776 T4584 680 808 936 1000

It is assumed that Tmax=1000 bits. It can be learned from Table 1 thatwhen Tmax=1000 bits, the TBS set is {T1=328, T2=536, T3=776, T4=1000}.If the terminal device needs to transmit only 400 bits of data, theterminal device may select, as Ts, T2=536 that can carry 400 bits andhas a smallest value. This is merely an example herein. The terminaldevice may alternatively select another TBS greater than 400 bits forsending.

In this example, the terminal device may first perform linear reductionon R1 based on Ts, to obtain a value f(Ts,R1) obtained after the linearreduction.

In an example, f(Ts,R1), Ts, and R1 may satisfy f(Ts,R1)=α*R1, where αis a scaling coefficient corresponding to Ts.

For example, α may be a ratio Ts/Tmax of Ts to Tmax. In other words,f(Ts,R1)=(Ts/Tmax)*R1.

Optionally, α may alternatively be a preset scaling coefficientcorresponding to Ts and Tmax. For example, corresponding to Table 1, avalue of a may be shown in Table 2.

TABLE 2 Tmax 328 408 504 584 680 808 936 1000 T1 1 1 0.75 0.75 0.5 0.50.5 0.5 T2 1 1 0.75 0.75 0.75 0.75 0.75 T3 1 1 1 1 1 1 T4 1 1 1 1 1

It is assumed that Tmax=1000 bits. When Ts=T2, it can be learned fromTable 2 that α=0.75.

After determining f(Ts,R1), the terminal device may round f(Ts,R1) basedon L, to obtain R2.

For example, the terminal device may round up f(Ts,R1) based on L. Inother words, f(Ts,R1) and L may satisfy R2=(L*┌f(Ts,R1)/L┐).Alternatively, the terminal device may round down f(Ts,R1) based on L.In other words, f(Ts,R1) and L may satisfy R2=(L*└f(Ts,R1)/L┘).Alternatively, the terminal device may round off f(Ts,R1) based on L. Inother words, f(Ts,R1) and L may satisfy

${R2} = {\left( {L*\left\lfloor {\frac{f\left( {{Ts},{R1}} \right)}{L} + 0.5} \right\rfloor} \right).}$

In another embodiment of this application, after determining f(Ts,R1),the terminal device may quantize f(Ts,R1) to a power of 2. For example,f(Ts,R1) is quantized to a value in {1, 2, 4, 8, 16, 32, 64, 128}.Proximity quantization may be performed, or f(Ts,R1) may be alwaysquantized to a minimum value greater than f(Ts,R1) or a maximum valueless than f(Ts,R1).

f(Ts,R1) is rounded based on L, so that an actual repetition quantity,calculated according to a preset scaling rule, of a transport blockwhose size is Ts is an integer multiple of L. This can ensure that theterminal device sends the data for a plurality of (R2/L) completesending cycles, and improve data transmission efficiency. If L is notrounded, there is a possibility that the terminal sends the data for anincomplete sending cycle, causing performance loss.

Further, in this example, step 303 may specifically include:

Step 303 a: Send the data based on the cyclic parameter L and R2.

An example in which uplink data is sent on an NPUSCH in NB-IoT is used.A transport block (or a codeword) corresponding to the NPUSCH is mappedto N_(RU) RUs, and one of the N_(RU) RUs corresponds to N_(slots) ^(UL)slots (slot) in terms of time. Therefore, content of one NPUSCHtransport block is mapped to N_(RU)*N_(slots) ^(UL) slots.

In this example, it is assumed that R1 is a repetition quantityindicated by the network device, and R2 is an actual repetition quantitycorresponding to Ts. The cyclic parameter L is calculated based on R1instead of R2: L=min (4,┌R1/2┐). When the terminal device sends the databased on the cyclic parameter L and R2, the NPUSCH transport block isfinally sent in N consecutive NB-IoT uplink slots, whereN=R2*N_(RU)*N_(slots) ^(UL). For ease of description, the N consecutiveuplink slots are numbered and denoted as Ni, where i=0, 1, 2, 3, . . . ,or N. During sending, the N slots are divided into R2/L groups, and eachgroup includes B consecutive uplink slots, where B=L*N_(RU)*N_(slots)^(UL). Content that is of the NPUSCH transport block and that is mappedto a

$\left\lfloor \frac{b}{L} \right\rfloor^{th}$slot (where b=0, 1, 2, . . . , or B−1) is sent in L uplink slots, andnumbers corresponding to the L uplink slots Ni are

${i = {{jB} + {2L\left\lfloor \frac{b}{2L} \right\rfloor} + {2l} + {{mod}\left( {\left\lfloor \frac{b}{L} \right\rfloor,2} \right)}}},$l=0, 1, . . . , L−1.

In this application, the NPUSCH transport block is mapped to X timeunits, where the time unit is two slots (that is, one subframe), and Xis

$\left\lfloor \frac{B}{2L} \right\rfloor.$One sending cycle corresponds to one group in this example. Contentcarried in each time unit (subframe) is repeated in L consecutivesubframes in one sending cycle. After content in

$\left\lfloor \frac{B}{2L} \right\rfloor*L$subframes is sent in one sending cycle of the

$\left\lfloor \frac{B}{2L} \right\rfloor*L$subframes (that is,

$\left\lfloor \frac{B}{2L} \right\rfloor*L*2$slots), the sending cycle is repeated for R2/L times. It should be notedherein that RVs of different sending cycles may be different. Forexample, an RV of a j^(th) sending cycle is rv_(idx)(j)=2□ mod(rv_(DCI)+j,2), where rv_(DCI) is an initial RV, and may be indicated ina RAR or DCI.

Correspondingly, the network device may calculate R2 in a same manner asthe terminal device does. Before step 305, the method further includesthe following steps.

Step 307: The network device determines R2 based on Ts, R1, and L, whereR2 is an integer multiple of L.

In this example, step 305 may specifically include:

Step 305 a: The network device receives the data based on L and R2.

It should be noted that when the network device calculates R2, becausethe network device cannot learn of Ts used by the terminal device, thenetwork device needs to assume a value of Ts, and then calculate R2based on different values. If the data sent by the terminal device canbe correctly received based on R2 calculated based on an assumed valueof Ts, it indicates that the assumed value of Ts is Ts used by theterminal device. When assuming the value of Ts, the network device mayalternatively determine an assumed range based on the TBS setcorresponding to Tmax.

In an example, the data transmission method in FIG. 3 and FIG. 4 may bespecifically applied to an early data transmission (early datatransmission during random access procedure, EDT) mechanism during arandom access procedure. The EDT mechanism supports the terminal devicein transmitting data during the random access procedure withoutestablishing an RRC connection. This avoids signaling interaction forestablishing the RRC connection. The EDT mechanism is very applicable todata, with a small data volume, in an uplink non-access stratum(non-access stratum, NAS) protocol data unit (protocol data unit, PDU).

For example, with reference to FIG. 3 , as shown in FIG. 5 , step 301may specifically include the following step:

Step 301 a: The network device sends a random access response (randomaccess response, RAR) message to the terminal device, where theinformation about R1 is carried in the RAR message.

In the EDT mechanism, the terminal device sends a physical random accesschannel (physical random access channel, PRACH) preamble sequence to thenetwork device on a specific PRACH preamble sequence resource. The PRACHpreamble sequence may be referred to as a first message (an MSG 1)during the random access procedure.

The specific PRACH preamble sequence resource is specially used forearly data transmission (Early Data Transmission, EDT). In this case,the terminal device sends the data during the random access procedure.

The network device detects the preamble sequence on the specific PRACHpreamble sequence resource, determines that data transmission is EDT,and determines to send a second message (an MSG 2) to the terminaldevice during the random access procedure. The MSG 2 includes the RARmessage for the terminal device. Because the network device cannotdetermine a volume of the data to be sent by the terminal device, thenetwork device allocates an uplink resource based on Tmax that isbroadcast through a system message, and allocates, through the RARmessage in the MSG 2 by using an uplink grant (UL grant), a resource andthe repetition quantity R1 that are to be used by the terminal device tosend a third message (an MSG 3).

After receiving the RAR message, the terminal device maps, according toa preset rule, Tmax to n TBSs that may be sent over the allocatedresource: T1, T2, . . . , Tn. For example, the preset rule may be shownin Table 1. When a maximum TBS allowed to be used to transmit the MSG 3and configured in the system message is 1000, a TBS set to which theterminal device maps Tmax according to the preset rule is {328, 536,776, 1000}.

The terminal device selects, based on the volume of the to-be-sent data,a most appropriate TBS from the n TBSs {T1, T2, . . . , Tn} that may besent as a target TBS (which may be denoted as a selected TBS, namely,Ts), where Ts is used to send a message in the MSG 3.

Specifically, the terminal device may select a TBS with a smallestpadding ratio (padding ratio) to send the MSG 3. In addition, the MSG 3includes a terminal ID of the terminal device and a NAS PDU of theto-be-sent data.

Step 303 may specifically include the following step:

Step 303 b: The terminal device transmits the data through the thirdmessage, namely, the MSG 3, during the random access procedure based onthe cyclic parameter L.

After determining the cyclic parameter L, the terminal device may sendthe MSG 3 on a physical uplink shared channel based on Ts.

An example in which the MSG 3 is sent on an NPUSCH in NB-IoT is used. Atransport block (or a codeword) corresponding to the MSG 3 is mapped toN_(RU) RUs, and one of the N_(RU) RUs corresponds to N_(slots) ^(UL)slots (slot) in terms of time. Therefore, content of an NPUSCH transportblock corresponding to one MSG 3 is mapped to N_(RU)*N_(slots) ^(UL)slots.

In this example, it is assumed that R1 is a repetition quantityindicated by the network device, and R2 is an actual repetition quantitycorresponding to Ts. The cyclic parameter L is calculated based on R1instead of R2: L=min (4,┌R1/2┐). When the terminal device sends the databased on the cyclic parameter L and R2, the NPUSCH transport block isfinally sent in N consecutive NB-IoT uplink slots, whereN=R2*N_(RU)*N_(slots) ^(UL). For ease of description, the N consecutiveuplink slots are numbered and denoted as Ni, where i=0, 1, 2, 3, . . . ,or N. During sending, the N slots are divided into R2/L groups, and eachgroup includes B consecutive uplink slots, where B=L*N_(RU)*N_(slots)^(UL). Content that is of the NPUSCH transport block and that is mappedto a

$\left\lfloor \frac{b}{L} \right\rfloor^{th}$slot (where b=0, 1, 2, . . . , or B−1) is sent in L uplink slots, andnumbers corresponding to the L uplink slots Ni are

${i = {{jB} + {2L\left\lfloor \frac{b}{2L} \right\rfloor} + {2l} + {{mod}\left( {\left\lfloor \frac{b}{L} \right\rfloor,2} \right)}}},$l=0, 1, . . . , L−1.

In this example, the transport block corresponding to the MSG 3 ismapped to X time units, where the time unit is two slots (that is, onesubframe), and X is

$\left\lfloor \frac{B}{2L} \right\rfloor.$One sending cycle corresponds to one group in this example. Contentcarried in each time unit (subframe) is repeated in L consecutivesubframes in one sending cycle. After content in

$\left\lfloor \frac{B}{2L} \right\rfloor*L$subframes is sent in one sending cycle of the

$\left\lfloor \frac{B}{2L} \right\rfloor*L$subframes (that is,

$\left\lfloor \frac{B}{2L} \right\rfloor*L*2$slots), the sending cycle is repeated for R2/L times. It should be notedherein that RVs of different sending cycles may be different. Forexample, an RV of a j^(th) sending cycle is rv_(idx)(j)=2□mod(rv_(DCI)+j,2), where rv_(DCI) is an initial RV, and may be indicatedin a RAR or DCI.

Correspondingly, step 305 may specifically include the following step:

Step 305 b: The network device receives the data through the MSG 3 basedon the cyclic parameter L.

FIG. 6A is a flowchart of another embodiment of a data transmissionmethod according to this application. The method provides a method forreducing R1, so that when Ts is less than Tmax, a terminal device canreduce R1 to obtain R2 (where R2<R1), to reduce sending powerconsumption of the terminal. The method includes the following steps.

Step 601: A network device sends, to the terminal device, informationabout a repetition quantity R1 corresponding to Tmax.

Step 602: The terminal device determines R2 based on Ts, R1, and acyclic parameter L, where R2 is an integer multiple of L, R2<R1, andTs<Tmax.

In this example, for a manner of determining Ts by the terminal device,refer to the manner of determining Ts by the terminal device in theembodiment shown in FIG. 5 . Details are not described herein again.

For a manner of determining the cyclic parameter L, refer to the mannerin which the terminal determines L based on R1 in the embodiment shownin FIG. 3 . Details are not described herein again.

Alternatively, in this example, the cyclic parameter L may be a presetfixed value.

After determining Ts and L, the terminal device may determine R2 basedon Ts, R1, and L. For a specific manner of determining R2 based on Ts,R1, and L, refer to the manner of determining R2 based on Ts, R1, and Lby the terminal device in the embodiment shown in FIG. 5 . Details arenot described herein again.

Step 603: The terminal device sends data based on R2.

When sending the data, the terminal device may specifically send thedata based on L and R2. For example, for specific implementation ofsending the data by the terminal device based on L and R2, refer to theforegoing description of step 303 a. Details are not described hereinagain.

Step 604: The network device determines R2 based on Ts, R1, and L, whereR2 is an integer multiple of L.

A value of Ts may be assumed by the network device. The network devicemay determine a TBS set based on Tmax, and then may successively assumethat values of TBSs in the TBS set are Ts.

For a specific manner in which the network device determines L anddetermines R2 based on Ts, R1, and L, refer to the manner in which theterminal device determines L and determines R2 based on Ts, R1, and L instep 602. Details are not described herein again.

Step 605: The network device receives the data based on R2.

When receiving the data, the network device may specifically receive thedata based on L and R2.

According to the data transmission method shown in FIG. 6A, a method forobtaining R2 (where R2<R1) by reducing R1 when Ts<Tmax is provided, toreduce the sending power consumption of the terminal device.

It should be noted that the data transmission method shown in FIG. 6Amay also be applied to an EDT RACH mechanism. For example, as shown inFIG. 6B, step 601 may specifically include the following step:

Step 601 a: The network device sends a RAR message to the terminaldevice, where the information about R1 is carried in the RAR message.

Step 603 may specifically include the following step:

Step 603 a: The terminal device sends the data through an MSG 3 based onR2.

Specifically, the terminal device may send the data through the MSG 3based on R2 and L. For specific implementation of sending the data bythe terminal device based on L and R2, refer to the foregoingdescription of step 303 b. Details are not described herein again.

Step 605 may specifically include the following step:

Step 605 a: The network device receives the data through the MSG 3 basedon R2.

When receiving the data through the MSG 3, the network device receivesthe data based on R2 and L.

The foregoing mainly describes the solutions provided in thisapplication from a perspective of interaction between the networkelements. It may be understood that to implement the foregoingfunctions, the terminal device and the network device each include acorresponding hardware structure and/or software module for performingeach function. A person skilled in the art should easily be aware that,in combination with units and algorithm steps of the examples describedin the embodiments disclosed in this specification, this application maybe implemented by hardware or a combination of hardware and computersoftware. Whether a function is performed by hardware or hardware drivenby computer software depends on particular applications and designconstraints of the technical solutions. A person skilled in the art mayuse different methods to implement the described functions for eachparticular application, but it should not be considered that theimplementation goes beyond the scope of this application.

FIG. 7 is a possible schematic structural diagram of a communicationsapparatus according to this application. The communications apparatusincludes a receiving unit 701, a processing unit 702, and a sending unit703.

The communications apparatus may be a functional module integrated on aterminal device or an external apparatus connected to the terminaldevice. When the communications apparatus runs, the terminal device canimplement the data transmission method in FIG. 3 to FIG. 5 , orimplement the data transmission method in FIG. 6A and FIG. 6B.

When the communications apparatus runs, the terminal device implementsthe data transmission method in FIG. 3 to FIG. 5 .

The receiving unit 701 is configured to receive information about arepetition quantity R1 corresponding to Tmax, where Tmax is a maximumtransport block size allowed to be used to transmit data.

The processing unit 702 is configured to determine a cyclic parameter Lbased on R1. The cyclic parameter L indicates that content carried ineach of a plurality of time units to which a transport block used totransmit the data is mapped is repeated in L consecutive time units,where a size of the transport block used to transmit the data is Ts, andTs<Tmax.

The sending unit 703 is configured to transmit the data based on thecyclic parameter L.

Optionally, that the processing unit 702 determines the cyclic parameterL based on R1 satisfies:

L=min (K,┌R1/2┐), where min represents taking a minimum value, K is apreset constant, and ┌ ┐ represents rounding up.

Optionally, the processing unit 702 is further configured to: before thesending unit 703 transmits the data based on the cyclic parameter L,determine R2 based on Ts, R1, and L, where R2 is an integer multiple ofL, and R2 is a total quantity of repeated transmissions of the contentcarried in each time unit when the data is sent.

The sending unit 703 is specifically configured to send the data basedon the cyclic parameter L and R2.

Optionally, that the processing unit 702 determines R2 based on Ts, R1,and L satisfies R2=(L*┌f(Ts,R1)/L┐), where ┌ ┐ represents rounding up.

Optionally, f(Ts,R1) satisfies f(Ts,R1)=(Ts/Tmax)*R1.

Optionally, the receiving unit 701 is specifically configured to receivea random access response RAR message, where the information about R1 iscarried in the RAR message.

The sending unit 703 is specifically configured to transmit the datathrough a third message, namely, an MSG 3, during a random accessprocedure based on the cyclic parameter L.

When the communications apparatus runs, the terminal device implementsthe data transmission method in FIG. 6A and FIG. 6B.

The receiving unit 701 is configured to receive information about arepetition quantity R1 corresponding to Tmax, where Tmax is a maximumtransport block size allowed to be used to transmit data.

The processing unit 702 is configured to determine R2 based on Ts, R1,and a cyclic parameter L, where R2 is an integer multiple of L. Thecyclic parameter L indicates that content carried in each of a pluralityof time units to which a transport block used to transmit the data ismapped is repeated in L consecutive time units. R2 is a total quantityof repeated transmissions of the content carried in each time unit whenthe data is sent. A size of the transport block used to transmit thedata is Ts, Ts<Tmax, and R2<R1.

The sending unit 703 is configured to send the data based on R2.

That the processing unit 702 determines R2 based on Ts, R1, and Lsatisfies R2=(L*┌f(Ts,R1)/L┐), where ┌ ┐ represents rounding up.

Optionally, f(Ts,R1) satisfies f(Ts,R1)=(Ts/Tmax)*R1.

Optionally, a value of the cyclic parameter L is fixed, or is determinedbased on R1.

Optionally, determining the cyclic parameter L based on R1 satisfiesL=min (K,┌R1/2┐), where min represents taking a minimum value, and K isa preset constant.

The communications apparatus may be a functional module integrated on anetwork device or an external apparatus connected to the network device.When the communications apparatus runs, the network device can implementthe data transmission method in FIG. 3 to FIG. 5 , or implement the datatransmission method in FIG. 6A and FIG. 6B.

When the communications apparatus runs, the network device implementsthe data transmission method in FIG. 3 to FIG. 5 .

The sending unit 703 is configured to send, to a terminal device,information about a repetition quantity R1 corresponding to Tmax, whereTmax is a maximum transport block size allowed to be used.

The processing unit 702 is configured to determine a cyclic parameter Lbased on R1. The cyclic parameter L indicates that content carried ineach of a plurality of time units to which a transport block used totransmit data is mapped is repeated in L consecutive time units, where asize of the transport block used to transmit the data is Ts, andTs<Tmax.

The receiving unit 701 is configured to receive the data based on thecyclic parameter L.

Optionally, that the processing unit 702 determines the cyclic parameterL based on R1 satisfies L=min (K,┌R1/2┐), where min represents taking aminimum value, and K is a preset constant.

Optionally, the processing unit 702 is further configured to: before thereceiving unit 701 receives the data based on the cyclic parameter L,determine R2 based on Ts, R1, and L, where R2 is an integer multiple ofL, and R2 is a total quantity of repeated transmissions of the contentcarried in each time unit when the terminal device sends the data.

The receiving unit 701 is specifically configured to receive the databased on the cyclic parameter L and R2.

Optionally, that the processing unit 702 determines R2 based on Ts, R1,and L satisfies R2=(L*┌f(Ts,R1)/L┐), where ┌ ┐ represents rounding up.

Optionally, f(Ts,R1) satisfies f(Ts,R1)=(Ts/Tmax)*R1.

Optionally, the sending unit 703 is specifically configured to send arandom access response RAR message to the terminal device, where theinformation about R1 is carried in the RAR message.

The receiving unit 701 is specifically configured to receive the datathrough a third message, namely, an MSG 3, during a random accessprocedure based on the cyclic parameter L.

When the communications apparatus runs, the network device implementsthe data transmission method in FIG. 6A and FIG. 6B.

The sending unit 703 is configured to send, to a terminal device,information about a repetition quantity R1 corresponding to Tmax, whereTmax is a maximum transport block size allowed to be used to transmitdata.

The processing unit 702 is configured to calculate R2 based on Ts, R1,and a cyclic parameter L, where R2 is an integer multiple of L. Thecyclic parameter L indicates that content carried in each of a pluralityof time units to which a transport block used to transmit the data ismapped is repeated in L consecutive time units. R2 is a total quantityof repeated transmissions of the content carried in each time unit whenthe data is sent. A size of the transport block used to transmit thedata is Ts, Ts<Tmax, and R2<R1.

The receiving unit 701 is configured to receive the data based on R2.

Optionally, the determining R2 based on Ts, R1, and L satisfiesR2=(L*┌f(Ts,R1)/L┐), where ┌ ┐ represents rounding up.

Optionally, f(Ts,R1) satisfies f(Ts,R1)=(Ts/Tmax)*R1.

Optionally, a value of the cyclic parameter L is fixed, or is determinedbased on R1.

Optionally, determining the cyclic parameter L based on R1 satisfiesL=min (K,┌R1/2┐), where min represents taking a minimum value, and K isa preset constant.

FIG. 8 is a schematic structural diagram of a communications apparatusaccording to this application. The communications apparatus includes aprocessor 801 and a memory 802.

The processor 801 may be a central processing unit (central processingunit, CPU), a general-purpose processor 801, a digital signal processor(digital signal processor, DSP), an application-specific integratedcircuit (application-Specific integrated circuit, ASIC), a fieldprogrammable gate array (field programmable gate array, FPGA) or anotherprogrammable logic device, a transistor logic device, a hardwarecomponent, or any combination thereof. The processor 801 may implementor execute various example logical blocks, modules, and circuitsdescribed with reference to content disclosed in this application.Alternatively, the processor 801 may be a combination of processorsimplementing a computing function, for example, a combination of one ormore microprocessors, or a combination of the DSP and a microprocessor.

Optionally, the communications apparatus may further include atransceiver 803, configured to support the communications apparatus insending and receiving data, signaling, or information in the foregoingdata transmission method, for example, sending or receiving theinformation about R1, sending or receiving the data, or the like.

Optionally, the communications apparatus may be a terminal device, ormay be a part of an apparatus in a terminal device, for example, a chipsystem in the terminal device. Optionally, the chip system is configuredto support the terminal device in implementing functions in theforegoing aspects, for example, generating, receiving, sending, orprocessing data and/or information in the foregoing methods. In apossible design, the chip system further includes a memory, and thememory is configured to store a program instruction and data that arenecessary for the terminal device. The chip system includes a chip, andmay further include another discrete device or circuit structure.

The processor 801, the transceiver 803, and the memory 802 are connectedto each other through a bus 804. The bus 804 may be a peripheralcomponent interconnect (peripheral component interconnect, PCI) bus 804,an extended industry standard architecture (extended industry standardarchitecture, EISA) bus 804, or the like. The bus 804 may be classifiedas an address bus, a data bus, a control bus, or the like. For ease ofrepresentation, only one thick line is used to represent the bus 804 inFIG. 8 , but this does not mean that there is only one bus or only onetype of bus.

The processor 801 is configured to couple to the memory 802, and readand execute instructions in the memory 802, to implement: receivinginformation about a repetition quantity R1 corresponding to Tmax, whereTmax is a maximum transport block size allowed to be used to transmitdata; determining a cyclic parameter L based on R1, where the cyclicparameter L indicates that content carried in each of a plurality oftime units to which a transport block used to transmit the data ismapped is repeated in L consecutive time units, and wherein a size ofthe transport block used to transmit the data is Ts, and Ts<Tmax; andtransmitting the data based on the cyclic parameter L.

Optionally, the determining a cyclic parameter L based on R1 satisfiesL=min (K,┌R1/2┐), where min represents taking a minimum value, and K isa preset constant.

Optionally, before transmitting the data based on the cyclic parameterL, the processor 801 further determines R2 based on Ts, R1, and L, whereR2 is an integer multiple of L, and R2 is a total quantity of repeatedtransmissions of the content carried in each time unit when the data issent. The transmitting the data based on the cyclic parameter Lincludes: transmitting the data based on the cyclic parameter L and R2.

Optionally, the determining R2 based on Ts, R1, and L satisfiesR2=(L*┌f(Ts,R1)/L┐), where ┌ ┐ represents rounding up.

Optionally, f(Ts,R1) satisfies f(Ts,R1)=(Ts/Tmax)*R1.

Optionally, the receiving information about a repetition quantity R1corresponding to Tmax includes: receiving a random access response RARmessage, where the information about R1 is carried in the RAR message.The transmitting the data based on the cyclic parameter L includes:transmitting the data through a third message, namely, an MSG 3, duringa random access procedure based on the cyclic parameter L.

Alternatively, the processor 801 is configured to couple to the memory802, and read and execute instructions in the memory 802, to implement:receiving information about a repetition quantity R1 corresponding toTmax, where Tmax is a maximum transport block size allowed to be used totransmit data; determining R2 based on Ts, R1, and a cyclic parameter L,where R2 is an integer multiple of L, the cyclic parameter L indicatesthat content carried in each of a plurality of time units to which atransport block used to transmit the data is mapped is repeated in Lconsecutive time units, R2 is a total quantity of repeated transmissionsof the content carried in each time unit when the data is sent, a sizeof the transport block used to transmit the data is Ts, Ts<Tmax, andR2<R1; and sending the data based on R2.

That the processing unit 1302 determines R2 based on Ts, R1, and Lsatisfies R2=(L*┌f(Ts,R1)/L┐), where ┌ ┐ represents rounding up.

Optionally, f(Ts,R1) satisfies f(Ts,R1)=(Ts/Tmax)*R1.

Optionally, a value of the cyclic parameter L is fixed, or is determinedbased on R1.

Optionally, determining the cyclic parameter L based on R1 satisfiesL=min (K,┌R1/2┐), where min represents taking a minimum value, and K isa preset constant.

Optionally, the communications apparatus may be a network device, or maybe a part of an apparatus in a network device, for example, a chipsystem in the network device. Optionally, the chip system is configuredto support the network device in implementing functions in the foregoingaspects, for example, generating, receiving, sending, or processing dataand/or information in the foregoing methods. In a possible design, thechip system further includes a memory, and the memory is configured tostore a program instruction and data that are necessary for the networkdevice. The chip system includes a chip, and may further include anotherdiscrete device or circuit structure. In this case, the processor 801 isconfigured to couple to the memory 802, and read and executeinstructions in the memory 802, to implement: sending, to a terminaldevice, information about a repetition quantity R1 corresponding toTmax, where Tmax is a maximum transport block size allowed to be used;determining a cyclic parameter L based on R1, where the cyclic parameterL indicates that content carried in each of a plurality of time units towhich a transport block used to transmit data is mapped is repeated in Lconsecutive time units, and wherein a size of the transport block usedto transmit the data is Ts, and Ts<Tmax; and receiving the data based onthe cyclic parameter L.

Optionally, the determining a cyclic parameter L based on R1 satisfiesL=min (K,┌R1/2┐), where min represents taking a minimum value, and K isa preset constant.

Optionally, before receiving the data based on the cyclic parameter L,the processor further determines R2 based on Ts, R1, and L, where R2 isan integer multiple of L, and R2 is a total quantity of repeatedtransmissions of the content carried in each time unit when the terminaldevice sends the data. The receiving the data based on the cyclicparameter L includes: receiving the data based on the cyclic parameter Land R2.

Optionally, the determining R2 based on Ts, R1, and L satisfiesR2=(L*┌f(Ts,R1)/L┐), where ┌ ┐ resents rounding up.

Optionally, f(Ts,R1) satisfies f(Ts,R1)=(Ts/Tmax)*R1.

Optionally, the sending, to a terminal device, information about arepetition quantity R1 corresponding to Tmax includes: sending a randomaccess response RAR message to the terminal device, where theinformation about R1 is carried in the RAR message. The receiving thedata based on the cyclic parameter L includes: receiving the datathrough a third message, namely, an MSG 3, during a random accessprocedure based on the cyclic parameter L.

Alternatively, the processor 801 is configured to couple to the memory802, and read and execute instructions in the memory 802, to implement:sending, to a terminal device, information about a repetition quantityR1 corresponding to Tmax, where Tmax is a maximum transport block sizeallowed to be used to transmit data; calculating R2 based on Ts, R1, anda cyclic parameter L, where R2 is an integer multiple of L, the cyclicparameter L indicates that content carried in each of a plurality oftime units to which a transport block used to transmit the data ismapped is repeated in L consecutive time units, R2 is a total quantityof repeated transmissions of the content carried in each time unit whenthe data is sent, a size of the transport block used to transmit thedata is Ts, Ts<Tmax, and R2<R1; and receiving the data based on R2.

Optionally, the determining R2 based on Ts, R1, and L satisfiesR2=(L*┌f(Ts,R1)/L┐), where ┌ ┐ represents rounding up.

Optionally, f(Ts,R1) satisfies f(Ts,R1)=(Ts/Tmax)*R1.

Optionally, a value of the cyclic parameter L is fixed, or is determinedbased on R1.

Optionally, determining the cyclic parameter L based on R1 satisfiesL=min (K,┌R1/2┐), where min represents taking a minimum value, and K isa preset constant.

In one example, method or algorithm steps described in combination withthe content disclosed in this application may be implemented byhardware, or may be implemented by a processor executing a softwareinstruction. The software instruction may include a correspondingsoftware module. The software module may be stored in a random accessmemory (Random Access Memory, RAM), a flash memory, a read-only memory(Read Only Memory, ROM), an erasable programmable read-only memory(Erasable Programmable ROM, EPROM), an electrically erasableprogrammable read-only memory (Electrically EPROM, EEPROM), a register,a hard disk, a removable hard disk, a compact disc read-only memory(CD-ROM), or any other form of storage medium well-known in the art. Forexample, a storage medium is coupled to a processor, so that theprocessor can read information from the storage medium or writeinformation into the storage medium. Certainly, the storage medium maybe a component of the processor. The processor and the storage mediummay be located in an ASIC. In addition, the ASIC may be located in acore network interface device. Certainly, the processor and the storagemedium may exist in the core network interface device as discretecomponents.

During specific implementation, this application further provides acomputer storage medium. The computer storage medium may store aprogram. When the program is executed, some or all of the steps in theembodiments of the data transmission method provided in this applicationmay be performed. The storage medium may be a magnetic disk, an opticaldisc, a read-only memory (English: read-only memory, ROM for short), arandom access memory (English: random access memory, RAM for short), orthe like.

This application further provides a computer program product includinginstructions. When the computer program product runs on a computer, thecomputer is enabled to perform some or all of the steps in theembodiments of the data transmission method provided in thisapplication.

A person skilled in the art may clearly understand that the technologiesin this application may be implemented by software in addition to anecessary general hardware platform. Based on such an understanding, thetechnical solutions of this application essentially or the partcontributing to the prior art may be implemented in a form of a softwareproduct. The computer software product may be stored in a storagemedium, such as a ROM/RAM, a magnetic disk, or an optical disc, andincludes instructions for instructing a computer device (which may be apersonal computer, a server, a VPN gateway, or the like) to perform themethods described in the embodiments or in some parts of the embodimentsof the present invention.

The foregoing descriptions are implementations of the present invention,but are not intended to limit the protection scope of the presentinvention.

What is claimed is:
 1. A data transmission method, wherein the methodcomprises: sending, to a communications apparatus, information about arepetition quantity (R1) corresponding to a maximum transport block size(Tmax) allowed to be used to transmit data; determining, based on R1, acyclic parameter (L) that indicates content carried in each of aplurality of time units to which a transport block used to transmit datais mapped is repeated in L consecutive time units, wherein a transportblock size actually used to transmit the data (Ts) is less than Tmax;and receiving the data based on the cyclic parameter (L), wherein thedetermining a cyclic parameter (L) comprises: when R1≥8, L=min(K,┌R1/2┐), wherein K is a preset constant, and ┌ ┐ represents roundingup; or when R1<8, L=1.
 2. The method according to claim 1, whereinbefore the receiving the data based on the cyclic parameter L, themethod further comprises: determining R2 based on Ts, R1, and L, whereinR2 is an integer multiple of L, and R2 is a total quantity of repeatedtransmissions of the content carried in each of the plurality of timeunits when the communications apparatus transmits the data; and whereinthe receiving the data based on the cyclic parameter (L) comprises:receiving the data based on the cyclic parameter (L) and R2.
 3. Themethod according to claim 2, wherein the determining R2 based on Ts, R1,and L satisfies: R2=(L*┌f(Ts,R1)/L┐), wherein ┌ ┐ represents roundingup.
 4. The method according to claim 3, wherein f(Ts,R1) satisfiesf(Ts,R1)=(Ts/Tmax)*R1.
 5. The method according to claim 1, wherein thesending, to a communications apparatus, information about a repetitionquantity (R1) corresponding to Tmax comprises: sending a random accessresponse (RAR) message to the communications apparatus, wherein theinformation about R1 is carried in the RAR message; and wherein thereceiving the data based on the cyclic parameter L comprises: receivingthe data through a third message (MSG 3), during a random accessprocedure based on the cyclic parameter (L).
 6. The method according toclaim 1, wherein the repetition quantity (R1) is a repetition quantityindicated in an uplink resource scheduling message.
 7. A firstcommunications apparatus, comprising: a processor, and a non-transitorycomputer-readable medium including executable instructions that, whenexecuted by the processor, enable the first communications apparatus toperform the operations of: sending, to a second communicationsapparatus, information about a repetition quantity (R1) corresponding toa maximum transport block size (Tmax) allowed to be used to transmitdata; determining, based on R1, a cyclic parameter (L) that indicatescontent carried in each of a plurality of time units to which atransport block used to transmit data is mapped is repeated in Lconsecutive time units, wherein a transport block size actually used totransmit the data (Ts) is less than Tmax; and receiving the data basedon the cyclic parameter (L), wherein the determining a cyclic parameter(L) comprises: when R1≥8, L=min (K,┌R1/2┐), wherein K is a presetconstant, and ┌ ┐ represents rounding up; or when R1<8, L=1.
 8. Thefirst communications apparatus according to claim 7, wherein theoperations further comprise: determining R2 based on Ts, R1, and L,wherein R2 is an integer multiple of L, and R2 is a total quantity ofrepeated transmissions of the content carried in each of the pluralityof time units when the second communications apparatus transmits thedata; and wherein the receiving the data based on the cyclic parameter(L) comprises: receiving the data based on the cyclic parameter (L) andR2.
 9. The first communications apparatus according to claim 8, whereinthe determining R2 based on Ts, R1, and L satisfies:R2=(L*┌f(Ts,R1)/L┐), wherein ┌ ┐ represents rounding up.
 10. The firstcommunications apparatus according to claim 9, wherein f(Ts,R1)satisfies f(Ts,R1)=(Ts/Tmax)*R1.
 11. The first communications apparatusaccording to claim 7, wherein the sending, to a second communicationsapparatus, information about a repetition quantity (R1) corresponding toTmax comprises: sending a random access response (RAR) message to thesecond communications apparatus, wherein the information about R1 iscarried in the RAR message; and wherein the receiving the data based onthe cyclic parameter L comprises: receiving the data through a thirdmessage (MSG 3), during a random access procedure based on the cyclicparameter (L).
 12. The first communications apparatus according to claim7, wherein the repetition quantity (R1) is a repetition quantityindicated in an uplink resource scheduling message.
 13. The firstcommunications apparatus according to claim 7, wherein the firstcommunications apparatus is a network device or a chip in the networkdevice, wherein the second communications apparatus is a terminal deviceor a chip in the terminal device.
 14. A system comprising: a firstcommunications apparatus, and a second communications apparatus, whereinthe network device is configured to: send, to the second communicationsapparatus, information about a repetition quantity (R1) corresponding toa maximum transport block size (Tmax) allowed to be used to transmitdata; determine, based on R1, a cyclic parameter (L) that indicatescontent carried in each of a plurality of time units to which atransport block used to transmit data is mapped is repeated in Lconsecutive time units, wherein a transport block size actually used bythe second communications apparatus to transmit the data (Ts) is lessthan Tmax; and receive the data based on the cyclic parameter (L);wherein the second communications apparatus is configured to: receivethe information about R1; determine, based on R1, the cyclic parameter(L) and transmit the data based on the cyclic parameter (L); and whereinthe determining a cyclic parameter (L) comprises: when R1≥8, L=min(K,┌R1/2┐) , wherein K is a preset constant, and ┌ ┐ represents roundingup; or when R1<8, L=1.
 15. The system according to claim 14, wherein thefirst communications apparatus and the second communications apparatusare further configured to: determine R2 based on Ts, R1, and L, whereinR2 is an integer multiple of L, and R2 is a total quantity of repeatedtransmissions of the content carried in each of the plurality of timeunits when the second communications apparatus transmits the data;wherein the receiving the data based on the cyclic parameter (L)comprises: receiving the data based on the cyclic parameter (L) and R2;and wherein the transmitting the data based on the cyclic parameter (L)comprises: transmitting the data based on the cyclic parameter (L) andR2.
 16. The system according to claim 15, wherein the determining R2based on Ts, R1, and L satisfies: R2=(L*┌f(Ts,R1)/L┐), wherein ┌ ┐represents rounding up.
 17. The system according to claim 16, whereinf(Ts,R1) satisfies f(Ts,R1)=(Ts/Tmax)* R1.
 18. The system according toclaim 14, wherein the sending, to the second communications apparatus,information about a repetition quantity (R1) corresponding to Tmaxcomprises: sending a random access response (RAR) message to the secondcommunications apparatus, wherein the information about R1 is carried inthe RAR message; wherein the receiving information about a repetitionquantity (R1) comprises: receiving the RAR message; wherein thetransmitting the data based on the cyclic parameter (L) comprises:transmitting the data through a third message (MSG3), during a randomaccess procedure based on the cyclic parameter (L); and wherein thereceiving the data based on the cyclic parameter (L) comprises:receiving the data through the MSG 3, during a random access procedurebased on the cyclic parameter (L).
 19. A data transmission method,wherein the method comprises: sending, by a first communicationsapparatus to a second communications apparatus, information about arepetition quantity (R1) corresponding to a maximum transport block size(Tmax) allowed to be used to transmit data; receiving, by the secondcommunications apparatus, the information about R1; determining, by thefirst communications apparatus and the second communications apparatus,based on R1, a cyclic parameter (L) that indicates content carried ineach of a plurality of time units to which a transport block used totransmit data is mapped is repeated in L consecutive time units, whereina transport block size actually used to transmit the data (Ts) is lessthan Tmax; and transmitting, by the second communications apparatus, thedata based on the cyclic parameter (L), receiving, by the firstcommunications apparatus, the data based on the cyclic parameter (L),wherein the determining a cyclic parameter (L) comprises: when R1≥8,L=min (K,┌R1/2┐), wherein K is a preset constant, and ┌ ┐ representsrounding up; or when R1<8, L=1.
 20. The method according to claim 19,wherein the method further comprises: determining, by the firstcommunications apparatus and the second communications apparatus, R2based on Ts, R1, and L, wherein R2 is an integer multiple of L, and R2is a total quantity of repeated transmissions of the content carried ineach of the plurality of time units when the second communicationsapparatus transmits the data; wherein the receiving the data based onthe cyclic parameter (L) comprises: receiving the data based on thecyclic parameter (L) and R2; and wherein the transmitting the data basedon the cyclic parameter (L) comprises: transmitting the data based onthe cyclic parameter (L) and R2.
 21. The method according to claim 20,wherein the determining R2 based on Ts, R1, and L satisfies:R2=(L*┌f(Ts,R1)/L┐), wherein ┌ ┐ represents rounding up.
 22. The methodaccording to claim 21, wherein f(Ts,R1) satisfies f(Ts,R1)=(Ts/Tmax)*R1.23. The method according to claim 19, wherein the sending, to the secondcommunications apparatus, information about a repetition quantity (R1)corresponding to Tmax comprises: sending a random access response (RAR)message to the second communications apparatus, wherein the informationabout R1 is carried in the RAR message; wherein the receivinginformation about a repetition quantity (R1) comprises: receiving theRAR message; wherein the transmitting the data based on the cyclicparameter (L) comprises: transmitting the data through a third message(MSG3), during a random access procedure based on the cyclic parameter(L); and wherein the receiving the data based on the cyclic parameter(L) comprises: receiving the data through the MSG 3, during a randomaccess procedure based on the cyclic parameter (L).